U.S. patent number 8,793,829 [Application Number 12/377,355] was granted by the patent office on 2014-08-05 for electric toothbrush.
This patent grant is currently assigned to Omron Healthcare Company Ltd.. The grantee listed for this patent is Yuji Asada, Yasutaka Murase, Jun Shimoyama, Tadashi Tone. Invention is credited to Yuji Asada, Yasutaka Murase, Jun Shimoyama, Tadashi Tone.
United States Patent |
8,793,829 |
Shimoyama , et al. |
August 5, 2014 |
Electric toothbrush
Abstract
An electric toothbrush capable of suppressing loss of vibration
energy while suppressing the vibration of the portion a user grips
with hand is provided. In an electric toothbrush including an inner
case, made up of an inner case main body and a motor holder,
mounted with various components including a motor; an outer case
which interiorly accommodates the inner case and which acts as a
portion the user grips with hand when brushing teeth; an eccentric
shaft, configured by a shaft main body and an eccentric member,
which center of gravity is arranged at a position shifted from a
shaft center and which rotates by a drive force of the motor; and a
vibration transmitting component for transmitting the vibration
generated with the rotation of the eccentric shaft to a brush
portion; where the vibration transmitting component is positioned
with respect to the outer case by point contacting the inner wall
surface of the outer case at a plurality of locations.
Inventors: |
Shimoyama; Jun (Uji,
JP), Murase; Yasutaka (Kyoto, JP), Tone;
Tadashi (Kyoto, JP), Asada; Yuji (Uji,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Shimoyama; Jun
Murase; Yasutaka
Tone; Tadashi
Asada; Yuji |
Uji
Kyoto
Kyoto
Uji |
N/A
N/A
N/A
N/A |
JP
JP
JP
JP |
|
|
Assignee: |
Omron Healthcare Company Ltd.
(Kyoto-shi, Kyoto, JP)
|
Family
ID: |
39135670 |
Appl.
No.: |
12/377,355 |
Filed: |
July 9, 2007 |
PCT
Filed: |
July 09, 2007 |
PCT No.: |
PCT/JP2007/063680 |
371(c)(1),(2),(4) Date: |
July 08, 2010 |
PCT
Pub. No.: |
WO2008/026383 |
PCT
Pub. Date: |
March 06, 2008 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20100269275 A1 |
Oct 28, 2010 |
|
Foreign Application Priority Data
|
|
|
|
|
Aug 29, 2006 [JP] |
|
|
2006-232528 |
Feb 27, 2007 [JP] |
|
|
2007-047831 |
|
Current U.S.
Class: |
15/22.1;
433/118 |
Current CPC
Class: |
A46B
13/023 (20130101); A61C 17/3481 (20130101) |
Current International
Class: |
A61C
17/22 (20060101) |
Field of
Search: |
;15/22.1 ;433/118
;310/81 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1682669 |
|
Oct 2005 |
|
CN |
|
6-34796 |
|
May 1994 |
|
JP |
|
7-24127 |
|
May 1995 |
|
JP |
|
8-66237 |
|
Mar 1996 |
|
JP |
|
8-117258 |
|
May 1996 |
|
JP |
|
10-192054 |
|
Jul 1998 |
|
JP |
|
2003-164473 |
|
Jun 2003 |
|
JP |
|
2004-57534 |
|
Feb 2004 |
|
JP |
|
2005131342 |
|
May 2005 |
|
JP |
|
2313310 |
|
Sep 2005 |
|
RU |
|
WO-02/054906 |
|
Jul 2002 |
|
WO |
|
Other References
Russian Decision on Grant mailed Sep. 29, 2010, directed to
Application No. 2009111223; 8 pages. cited by applicant .
Russian Office Action Issued Apr. 13, 2010 directed to counterpart
application No. 2009111223/20(015266); 6 pages. cited by applicant
.
Orlov P.I. (1988). Principles of Design. 346-347. cited by
applicant .
Chinese Office Action mailed Jun. 29, 2011, directed to counterpart
Application No. 200780032526.6; 6 pages. cited by
applicant.
|
Primary Examiner: Doan; Robyn
Assistant Examiner: Nobrega; Tatiana
Attorney, Agent or Firm: Morrison & Foerster LLP
Claims
The invention claimed is:
1. An electric toothbrush comprising: an inner case which is
mounted with components including a drive source; an outer case
which interiorly accommodates the inner case, and which becomes a
portion a user grips with hand when brushing teeth; an eccentric
shaft which center of gravity is arranged at a position shifted
from a shaft center and which rotates by a drive force of the drive
source; and a vibration transmitting component which transmits a
vibration generated with a rotation of the eccentric shaft to a
brush portion, wherein the vibration transmitting component is
positioned with respect to the outer case by point contacting an
inner wall surface of the outer case at a plurality of locations,
and the vibration transmitting component includes, a stem, made
from a hard material, arranged with an eccentric shaft bearing; a
holder, made from a hard material, arranged so as not to contact
the stem and fixed to the inner case; and an elastic member having
an interposing portion interposed so as to be sandwiched between
the stem and the holder, and a plurality of projecting portions
that point contacts the inner wall surface of the outer case.
2. The electric toothbrush according to claim 1, wherein the
elastic member is a molded article having elastomer as a raw
material; and the vibration transmitting component is integrally
molded by insert molding with the stem and the holder as insert
parts.
3. The electric toothbrush according to claim 1 or 2, wherein a
rotation-preventing structure is arranged between the stem and the
elastic member, and between the elastic member and the holder.
4. The electric toothbrush according to claim 1, wherein a seal
ring for sealing a clearance between the outer case and the
vibration transmitting component is arranged.
5. The electric toothbrush according to claim 1, wherein a space
region for storing a lubricant to supply to a slidably moving
portion of the eccentric shaft and the bearing is arranged at a
distal end portion in an interior of the stem.
6. The electric toothbrush according to claim 5, wherein the space
region is positioned closer to a distal end side than the bearing
is; and the distal end of the eccentric shaft projects out to a
space region side beyond the bearing.
7. The electric toothbrush according to claim 1, comprising: a
brush component which includes a tubular portion to be attached to
the vibration transmitting component and a brush portion arranged
at a distal end of the tubular portion, and which is configured to
be removable with respect to the vibration transmitting component;
wherein with the brush component attached to the vibration
transmitting component, a vicinity of one end and a vicinity of the
other end of the tubular portion contact the stem, and a clearance
is formed between an inner wall surface of the tubular portion and
an outer wall surface of the stem at an intermediate portion.
8. The electric toothbrush according to claim 7, wherein the
contact between the tubular portion and the stem is point contact
at a plurality of locations with respect to a peripheral direction,
or line contact at a plurality of locations with respect to the
peripheral direction.
9. The electric toothbrush according to claim 1, wherein the
eccentric shaft is configured by a shaft main body and an eccentric
member arranged on the brush portion side than the shaft main body;
and the shaft main body includes, a first shaft member connected to
the eccentric member, and a second shaft member connected to a side
opposite to the eccentric member with respect to the first shaft
member, and having higher flexibility than the first shaft
member.
10. The electric toothbrush according to claim 9, wherein a central
portion of the second shaft member includes a small diameter
portion, which outer diameter is smaller than an outer diameter of
the first shaft member.
11. The electric toothbrush according to claim 9, wherein a central
portion of the second shaft member includes a small diameter
portion, which outer diameter is smaller than an outer diameter of
the first shaft member.
12. An electric toothbrush comprising: an inner case which is
mounted with components including a drive source; an outer case
which interiorly accommodates the inner case, and which becomes a
portion a user grips with hand when brushing teeth; an eccentric
shaft which center of gravity is arranged at a position shifted
from a shaft center and which rotates by a drive force of the drive
source; and a vibration transmitting component which transmits a
vibration generated with a rotation of the eccentric shaft to a
brush portion, wherein the vibration transmitting component is
positioned with respect to the outer case by point contacting an
inner wall surface of the outer case at a plurality of locations,
and the vibration transmitting component includes, a stem, made
from a hard material, arranged with the eccentric shaft bearing;
and a holder, made from an elastic material, fixed to the inner
case and having a plurality of projecting portions that point
contact the inner wall surface of the outer case.
13. The electric toothbrush according to claim 12, wherein a seal
ring for sealing a clearance between the outer case and the
vibration transmitting component is arranged.
14. The electric toothbrush according to claim 12, wherein the
eccentric shaft is configured by a shaft main body and an eccentric
member arranged on the brush portion side than the shaft main body;
and the shaft main body includes, a first shaft member connected to
the eccentric member, and a second shaft member connected to a side
opposite to the eccentric member with respect to the first shaft
member, and having higher flexibility than the first shaft
member.
15. An electric toothbrush comprising: an eccentric shaft which
center of gravity is arranged at a position shifted from a shaft
center, the eccentric shaft having a free end, a junction end and
an eccentric member that is shifted from the shaft center so that
an empty space exists at the shaft center between the free end and
the junction end; a driver connected to the junction end; an
elongated vibration transmitting component which transmits
vibration generated with a rotation of the eccentric shaft to a
brush portion; and a brush component which includes a tubular
portion having a closed end and an open end so as to be attached to
the elongated vibration transmitting component, and a brush portion
arranged at the closed end of the tubular portion, the tubular
portion being configured to be detachably mounted on the elongated
vibration transmitting component such that the elongated vibration
transmitting component, where the eccentric shaft is housed, is
inserted into the tubular portion wherein the vibration
transmitting component includes a stem arranged with only one
eccentric shaft bearing, the bearing being located close to a
distal end of the stem for supporting the free end, and no other
bearing being located in the stem along the eccentric shaft, a
space region for storing a lubricant to supply to a slidably moving
portion of the eccentric shaft and the bearing is arranged at a
distal end portion in an interior of the stem, the space region is
positioned closer to a distal end side than the bearing is, and the
free end of the eccentric shaft projects out to a space region side
beyond the bearing, a first portion of the tubular portion near the
closed end thereof and a second portion of the tubular portion near
the open end thereof firmly contact the elongated vibration
transmitting component, with a middle portion of the tubular
portion between the first portion and the second portion being
spaced away from the elongated vibration transmitting component,
defining a clearance between an inner wall surface of the tubular
portion and an outer wall surface of the elongated vibration
transmitting component.
Description
CROSS REFERENCE TO RELATED APPLICATION
This application is a National Stage application of
PCT/JP2007/063680, filed on Jul. 9, 2007, which claims the benefit
of priority of Japanese Application Nos. 2006-232528, filed Aug.
29, 2006, and 2007-047831, filed Jan. 27, 2007, the entire contents
of these applications hereby incorporated by reference.
TECHNICAL FIELD
The present invention relates to an electric toothbrush.
BACKGROUND ART
An electric toothbrush internally equipped with a vibration source
and configured to transmit the vibration from the vibration source
to a brush portion is conventionally known. In such an electric
toothbrush, the brush portion needs to be sufficiently vibrated to
exhibit an effect of brushing teeth and to enable a user
himself/herself to sufficiently have actual feeling of brushing
teeth. If the vibration of the portion the user grips is too large
when brushing teeth, the user sometimes feels unpleasant, and thus
it is desirable that the relevant portion does not vibrate too
much.
In order to sufficiently vibrate the brush portion and to not
vibrate the portion the user grips with hand as much, consideration
is made in arranging a vibration proof member for absorbing the
vibration near the end on the opposite side of a component at which
distal end the brush portion is arranged. However, this is not
desirable in terms of energy efficiency since absorbing the
vibration with the vibration proof member leads to losing some of
the vibration energy generated by the vibration source.
Therefore, suppressing the vibration of the portion the user grips
with hand while sufficiently vibrating the brush portion and
suppressing the loss of vibration energy involve technical
difficulty.
A technique of vibrating the brush portion by arranging an
eccentric shaft bearing near the brush portion is known (Patent
Document 3). However, such a technique has problems such as
increase in slidable movement resistance and increase in an
operation sound and vibration.
The related technique includes those disclosed in Patent Documents
1, 2, and 3.
[Patent Document 1] Japanese Examined Patent Publication No.
6-34796
[Patent Document 2] Japanese Unexamined Patent Publication No.
8-117258
[Patent Document 3] Japanese Unexamined Patent Publication No.
10-192054
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
It is an object of the present invention to provide an electric
toothbrush capable of suppressing loss of vibration energy while
suppressing vibration of the portion a user grips with hand.
Means for Solving the Problems
The present invention adopts the following means to solve the above
problems.
An electric toothbrush of the present invention relates to an
electric toothbrush including an inner case which is mounted with
various components including a drive source; an outer case which
interiorly accommodates the inner case, and which becomes a portion
a user grips with hand when brushing teeth; an eccentric shaft
which center of gravity is arranged at a position shifted from a
shaft center and which rotates by a drive force of the drive
source; and a vibration transmitting component which transmits a
vibration generated with the rotation of the eccentric shaft to a
brush portion; wherein the vibration transmitting component is
positioned with respect to the outer case by point contacting an
inner wall surface of the outer case at a plurality of
locations.
When point contacting the members, it is physically impossible to
contact at a perfect point, and contact is made, in reality, at a
surface of a very small area. Therefore, "point contact" in the
present invention includes area contact of a very small area.
According to the present invention, the vibration transmitting
component is positioned with respect to the outer case by point
contacting the inner wall surface of the outer case at a plurality
of locations. Thus, transmission of the vibration of the vibration
transmitting component to the outer case can be suppressed.
Therefore, the outer case, which becomes the portion the user grips
with hand when brushing teeth, is suppressed from vibrating.
The movement of the vibration transmitting component is not greatly
limited by the outer case. Therefore, the vibration transmitting
component can be freely vibrated without being greatly restricted
by the outer case. Accordingly, the loss of vibration energy can be
suppressed.
Furthermore, the vibration transmitting component may include a
stem, made from a hard material, arranged with an eccentric shaft
bearing; a holder, made from a hard material, arranged so as not to
contact the stem and fixed to the inner case; and an elastic member
having an interposing portion interposed so as to be sandwiched
between the stem and the holder, and a plurality of projecting
portions that point contacts the inner wall surface of the outer
case.
According to such a configuration, the vibration transmitting
component is elastically point contacted to the inner wall surface
of the outer case. Therefore, the movement of the vibration
transmitting component is more reliably prevented from being
limited by the outer case. Furthermore, the vibration of the stem
is suppressed from being transmitted to the holder since the
interposing portion of the elastic member is interposed between the
stem and the holder. Thus, the vibration of the stem is suppressed
from being transmitted to the inner case through the holder.
The vibration transmitting component can be more reliably fixed to
the inner case since the holder to be fixed to the inner case is
made from a hard material. Moreover, the original function of the
vibration transmitting component of transmitting the vibration
generated with the rotation of the eccentric shaft to the brush
portion is sufficiently exhibited since the stem arranged with the
eccentric shaft bearing is made from a hard material.
Preferably, the elastic member is a molded article having elastomer
as a raw material; and the vibration transmitting component is
integrally molded by insert molding with the stem and the holder as
insert parts.
In this manner, the vibration transmitting component can be handled
as one component. The sealability between the stem and the elastic
member, and between the elastic member and the holder can be
sufficiently exhibited.
Furthermore, a rotation-preventing structure may be arranged
between the stem and the elastic member, and between the elastic
member and the holder.
Therefore, the members are prevented from shifting in a rotating
direction.
The vibration transmitting component suitably includes a stem, made
from a hard material, arranged with the eccentric shaft bearing;
and a holder, made from an elastic material, fixed to the inner
case and having a plurality of projecting portions that point
contact the inner wall surface of the outer case.
When adopting such a configuration as well, the vibration
transmitting component elastically point contacts the inner wall
surface of the outer case. Therefore, the movement of the vibration
transmitting component is more reliably prevented from being
limited by the outer case. The vibration of the stem is suppressed
from being transmitted to the inner case. Furthermore, the original
function of the vibration transmitting component of transmitting
the vibration generated with the rotation of the eccentric shaft to
the brush portion is sufficiently exhibited since the stem arranged
with the eccentric shaft bearing is made from a hard material.
A seal ring for sealing a clearance between the outer case and the
vibration transmitting component is preferably arranged.
Therefore, water and the like are prevented from entering inside
from between the outer case and the vibration transmitting
component.
A space region for storing a lubricant to supply to a slidably
moving portion of the eccentric shaft and the bearing is preferably
arranged at a distal end portion in an interior of the stem.
Thus, the lubricant can be interposed over a long period of time at
the slidably moving portion of the eccentric shaft and the bearing
by storing the lubricant in the space region. Thus, the slidably
moving state of the eccentric shaft and the bearing can be
stabilized over a long period of time. Therefore, the vibration
state of each portion can be stabilized over a long period of time.
Moreover, increase in the slidable movement resistance can be
suppressed, generation of abnormal noise can be suppressed, and
increase in vibration can be suppressed.
Preferably, the space region is positioned on a distal end side
than the bearing; and the distal end of the eccentric shaft
projects out to the space region side than the bearing.
Therefore, the distal end of the eccentric shaft is in a state of
contacting the lubricant, whereby the lubricant can be actively
introduced to the slidably moving portion of the eccentric shaft
and the bearing.
Moreover, a brush component which includes a tubular portion to be
attached to the vibration transmitting component and a brush
portion arranged at a distal end of the tubular portion, and which
is configured to be removable with respect to the vibration
transmitting component is further arranged; wherein with the brush
component attached to the vibration transmitting component, a
vicinity of one end and a vicinity of the other end of the tubular
portion contact the stem, and a clearance is formed between an
inner wall surface of the tubular portion and an outer wall surface
of the stem at an intermediate portion.
Therefore, the location the vibration is directly transmitted from
the vibration transmitting component to the brush component can be
a limited portion (i.e., contacting portion). The efficiency of the
vibration transmission with respect to the brush portion thus can
be enhanced as much as possible, and the transmission of vibration
to the portion the user grips with hand when brushing teeth can be
suppressed.
The contact between the tubular portion and the stem may be point
contact at a plurality of locations with respect to a peripheral
direction, or line contact at a plurality of locations with respect
to the peripheral direction.
Therefore, the location the vibration is directly transmitted from
the vibration transmitting component to the brush component can be
a more limited portion.
The "point contact" includes area contact of a very small area in
the present invention, as described above. When contacting the
members by line contact, it is physically impossible to contact at
a perfect line, and contact is made, in reality, at a surface of a
very small area. Therefore, "line contact" in the present invention
includes area contact of very small area, similar to the point
contact.
An electric toothbrush of the present invention relates to an
electric toothbrush including an eccentric shaft which center of
gravity is arranged at a position shifted from a shaft center; and
a vibration transmitting component which transmits vibration
generated with the rotation of the eccentric shaft to a brush
portion; wherein the vibration transmitting component includes a
stem arranged with an eccentric shaft bearing; and a space region
for storing a lubricant to supply to a slidably moving portion of
the eccentric shaft and the bearing is arranged at a distal end
portion in an interior of the stem.
According to the present invention, the lubricant can be interposed
over a long period of time at the slidably moving portion of the
eccentric shaft and the bearing by storing the lubricant in the
space region. Thus, the slidably moving state of the eccentric
shaft and the bearing can be stabilized over a long period of time.
Therefore, the vibration state of each portion can be stabilized
over a long period of time. Moreover, increase in the slidable
movement resistance can be suppressed, generation of abnormal noise
can be suppressed, and increase in vibration can be suppressed.
Preferably, the space region is positioned on a distal end side
than the bearing; and the distal end of the eccentric shaft
projects out to the space region side than the bearing.
The distal end of the eccentric shaft is thus in a state of
contacting the lubricant. Therefore, the lubricant can be actively
introduced to the slidably moving portion of the eccentric shaft
and the bearing.
An electric toothbrush of the present invention relates to an
electric toothbrush including an eccentric shaft which center of
gravity is arranged at a position shifted from a shaft center; a
vibration transmitting component which transmits vibration
generated with the rotation of the eccentric shaft to a brush
portion; and a brush component which includes a tubular portion to
be attached to the vibration transmitting component and a brush
portion arranged at a distal end of the tubular portion, and which
is configured to be removable with respect to the vibration
transmitting component; wherein the vibration transmitting
component includes a stem arranged with the eccentric shaft
bearing; and with the brush component attached to the vibration
transmitting component, a vicinity of one end and a vicinity of the
other end of the tubular portion contact the stem, and a clearance
is formed between an inner wall surface of the tubular portion and
an outer wall surface of the stem at an intermediate portion.
According to the present invention, the location the vibration is
directly transmitted from the vibration transmitting component to
the brush component can be a limited portion (i.e., contacting
portion). Therefore, the efficiency of the vibration transmission
with respect to the brush portion can be enhanced as much as
possible, and the transmission of vibration to the portion the user
grips with hand when brushing teeth can be suppressed.
The contact between the tubular portion and the stem may be point
contact at the plurality of locations with respect to a peripheral
direction, or line contact at the plurality of locations with
respect to the peripheral direction.
Therefore, the location the vibration is directly transmitted from
the vibration transmitting component to the brush component can be
a more limited portion.
The eccentric shaft is preferably configured by a shaft main body
and an eccentric member arranged on the brush portion side than the
shaft main body; and the shaft main body includes a first shaft
member connected to the eccentric member, and a second shaft member
connected to a side opposite to the eccentric member with respect
to the first shaft member, and having higher flexibility than the
first shaft member.
The vibration generated by the eccentric member is thus absorbed by
the second shaft member. Therefore, the transmission of vibration
to the portion the user grips with hand when brushing teeth can be
further suppressed.
A central portion of the second shaft member preferably includes a
small diameter portion, which outer diameter is smaller than an
outer diameter of the first shaft member.
Therefore, the transmission of vibration from the eccentric member
side to the portion side the user grips with hand when brushing
teeth can be further suppressed.
Each of the above configuration may be combined as much as possible
for use.
According to the present invention, the suppression in the loss of
vibration energy can be achieved while suppressing the vibration of
the portion the user grips with hand, as described above.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an outer appearance of an electric
toothbrush according to a first embodiment of the present
invention.
FIG. 2 is a perspective view showing a state in which a cap and a
brush component are detached in the electric toothbrush according
to the first embodiment of the present invention.
FIG. 3 is an exploded perspective view of the electric toothbrush
according to the first embodiment of the present invention.
FIG. 4 is a cross-sectional view of the electric toothbrush
according to the first embodiment of the present invention.
FIG. 5 is a perspective view showing a fixed structure of an inner
case and a vibration transmitting component in the electric
toothbrush according to the first embodiment of the present
invention.
FIG. 6 is a perspective view further exploded for the vibration
transmitting component and some components mounted on the inner
case in the electric toothbrush according to the first embodiment
of the present invention.
FIG. 7 is a plan view of the vibration transmitting component
according to the first embodiment of the present invention.
FIG. 8 is a cross-sectional view of the vibration transmitting
component according to the first embodiment of the present
invention.
FIG. 9 is a perspective view of the vibration transmitting
component according to the first embodiment of the present
invention seen from the distal end side.
FIG. 10 is a perspective view of the vibration transmitting
component according to the first embodiment of the present
invention seen from the rear end side.
FIG. 11 is a cross-sectional view of a vibration transmitting
component according to a second embodiment of the present
invention.
FIG. 12 is a cross-sectional view of a vibration transmitting
component according to a third embodiment of the present
invention.
FIG. 13 is one part of a schematic cross-sectional view of an
electric toothbrush according to a fourth embodiment of the present
invention.
FIG. 14 is one part of a schematic cross-sectional view of an
electric toothbrush according to a fifth embodiment of the present
invention.
FIG. 15 is a partial perspective view of the vicinity of the brush
component of the electric toothbrush according to the fifth
embodiment of the present invention.
FIG. 16 is a partial perspective side view of the vicinity of the
brush component of the electric toothbrush according to the fifth
embodiment of the present invention.
FIG. 17 is a partially cut perspective view of the brush component
of the electric toothbrush according to the fifth embodiment of the
present invention.
FIG. 18 is a view describing the contacting state of the brush
component and the stem in the electric toothbrush according to the
fifth embodiment of the present invention.
DESCRIPTION OF REFERENCE SYMBOLS
10 Electric toothbrush 100, 100a, 100b Vibration transmitting
component 110 Stem 111 Fixing portion 112 Projection 113 Fit-in
projection 115 Space region 120 Holder 121 Pass-through hole 122
Pass-through hole 130 Elastic member 131 Projecting portion 132
Interposing portion 140 Holder 141 Projecting portion 142
Pass-through hole 150 Stem portion 151 Fixing portion 152
Projecting portion 153 Pass-through hole 200 Brush component 201
Tubular portion 201a Plane portion 202 Brush portion 203 Groove 301
Outer case 301a Male screw 302 Cap 302a Female screw 303 Inner case
main body 303a Switch 304 Motor holder 304a Lock projection 305
Motor 306 Shaft main body 307 Eccentric member 307a Distal end (of
eccentric shaft) 308 First shaft member 309 Second shaft member
309a First fit-in portion 309b Second fit-in portion 309c Small
diameter portion 400 Bearing B Machine screw C Clearance D Battery
F Vicinity of front end O Lubricant oil R Vicinity of rear end S
Switch button S1 Seal ring S2 Seal ring X Slidably moving
portion
BEST MODE FOR CARRYING OUT THE INVENTION
Best modes for carrying out the present invention will now be
illustratively described in detail below based on embodiments with
reference to the drawings. The dimension, material, shape, relative
arrangement, and the like of components described in the
embodiments are not intended to limit the scope of the present
invention unless specific description is particularly made.
(First Embodiment)
An electric toothbrush according to a first embodiment of the
present invention will be described with reference to FIGS. 1 to
10.
<Schematic Configuration of Electric Toothbrush>
The schematic configuration of the electric toothbrush according to
the first embodiment of the present invention will be described
with reference to FIGS. 1 and 2. FIG. 1 is a perspective view of an
outer appearance of the electric toothbrush according to the first
embodiment of the present invention. FIG. 2 is a perspective view
showing a state in which a cap and a brush component are detached
in the electric toothbrush according to the first embodiment of the
present invention.
An electric toothbrush 10 according to the present embodiment
includes an outer case 301 serving as a portion the user grips with
hand when brushing teeth, a brush component 200 arranged on the
distal end side of the outer case 301, and a cap 302 arranged on
the rear end side of the outer case 301.
The outer case 301 is configured by a tubular member, where an
inner case mounted with various components is accommodated therein.
The outer case 301 is arranged with a switch button S for switching
the power to ON or OFF.
A vibration transmitting component 100 for transmitting the
vibration to the brush component 200 is arranged so as to project
out from the inside to the outside of the outer case 301 from the
distal end side of the outer case 301. The brush component 200 is
attached to the vibration transmitting component 100 so as to cover
the vibration transmitting component 100.
The brush component 200 includes a tubular portion 201 to be
attached to the vibration transmitting component 100, and a brush
portion 202 arranged at the distal end of the tubular portion 201.
The brush component 200 is a consumable part, and is configured to
be removable with respect to the vibration transmitting component
100 so as to be appropriately changed with a new one.
One part of an inner case main body 303 configuring the inner case
is arranged to project out from the inside to the outside of the
outer case 301 from the rear end side of the outer case 301.
Therefore, one part of the inner case main body 303 is opened by
detaching the cap 302 thereby enabling a battery D to be
changed.
<Internal Configuration of Electric Toothbrush>
The internal configuration of the electric toothbrush 10 according
to the first embodiment of the present invention will be described
with particular reference to FIGS. 3 to 6. FIG. 3 is an exploded
perspective view of the electric toothbrush according to the first
embodiment of the present invention. FIG. 4 is a cross-sectional
view of the electric toothbrush according to the first embodiment
of the present invention. FIG. 4 is a cross-sectional view
(cross-sectional view in longitudinal direction) cut so as to pass
through a center axis of the electric toothbrush. FIG. 5 is a
perspective view showing a fixed structure of the inner case and
the vibration transmitting component in the electric toothbrush
according to the first embodiment of the present invention. FIG. 6
is a perspective view further exploded for the vibration
transmitting component and some components mounted on the inner
case in the electric toothbrush according to the first embodiment
of the present invention.
The inner case including the inner case main body 303 and a motor
holder 304 is accommodated inside the outer case 301. The inner
case is mounted with a motor 305 serving as a drive source, and the
battery D serving as a power supply for supplying electricity to
the motor 305.
The inner case main body 303 is arranged with a switch 303a for
switching the power to ON or OFF. The switch 303a arranged on the
inner case main body 303 is pushed when the switch button S
arranged on the outer case 301 is pushed.
The motor 305 is fixed to the motor holder 304 by a machine screw
B, and such a motor holder 304 is fixed to the inner case main body
303 by the machine screw B as shown in FIG. 5. An eccentric shaft
configured by a shaft main body 306 and an eccentric member 307 is
coaxially fixed with respect to the shaft of the motor 305 fixed to
the motor holder 304.
The distal end of the eccentric shaft (more specifically, distal
end of eccentric member 307) is supported in a freely rotating
state by a bearing 400 arranged inside the vibration transmitting
component 100. A very small clearance is formed between the
eccentric shaft and the bearing 400.
The motor holder 304 has a plurality of lock projections 304a. A
plurality of pass-through holes 121 to which the lock projections
304a lock are formed in the vibration transmitting component 100.
The plurality of lock projections 304a are locked to the plurality
of pass-through holes 121 so that the vibration transmitting
component 100 is fixed to the motor holder 304 configuring the
inner case.
The vibration transmitting component 100 is fixed to the inner case
including the inner case main body 303 and the motor holder 304 in
such a manner (see FIG. 3). With the vibration transmitting
component 100 fixed to the inner case, the vibration transmitting
component 100 fixed to the inner case is inserted from an opening
on the rear end side of the outer case 301, and the vibration
component 100 and the inner case are attached to the outer case 301
such that the vibration transmitting component 100 projects out
from an opening on the distal end side of the outer case 301.
A seal ring S2 is attached to the vibration transmitting component
100. When the vibration transmitting component 100 is attached to
the outer case 301, the seal ring S2 closely attaches to the inner
peripheral surface near the open end of the outer case 301. The gap
between the outer case 301 and the vibration transmitting component
100 is thus sealed, thereby preventing water and the like from
entering from between.
A male screw 301a is provided on the outer peripheral surface of
the rear end of the outer case 301, and a female screw 302a is
provided at the inner periphery of the open end of the cap 302. The
cap 302 is fixed to the outer case 301 by screw-fitting the male
screw 301a and the female screw 302a.
A seal ring S1 is attached to a region corresponding to the distal
end of the cap 302 at the outer peripheral surface of the outer
case 301. The distal end of the cap 302 thus closely attaches to
the seal ring S1 when the cap 302 is fixed to the outer case 301.
The gap between the outer case 301 and the cap 302 is thus sealed,
thereby preventing water and the like from entering inside from
between.
<Vibration Transmitting Component>
The vibration transmitting component 100 according to the first
embodiment of the present invention will be more specifically
described with particular reference to FIGS. 7 to 10. FIG. 7 is a
plan view of the vibration transmitting component according to the
first embodiment of the present invention. FIG. 8 is a
cross-sectional view of the vibration transmitting component
according to the first embodiment of the present invention. FIG. 8
is a cross-sectional view taken along AA of FIG. 7. FIG. 9 is a
perspective view of the vibration transmitting component according
to the first embodiment of the present invention seen from the
distal end side. FIG. 10 is a perspective view of the vibration
transmitting component according to the first embodiment of the
present invention seen from the rear end side.
The vibration transmitting component 100 according to the present
embodiment is configured by a stem 110 made from a hard material
(e.g., resin material), a holder 120 made from a hard material
(e.g., resin material) arranged so as not to contact the stem 110,
and an elastic member 130 using elastomer as a raw material.
In the vibration transmitting component 100 according to the
present embodiment, the elastic member 130 is a molded article
molded by a die. That is, the vibration transmitting component 100
is obtained by integrally molding the elastic member 130 by insert
molding with the stem 110 and the holder 120 as insert parts.
The stem 110 is a tubular member having a closed distal end, where
a fixing portion 111 for fixing the bearing 400 is arranged at the
distal end in the interior of the tube. A plurality of projections
112 are arranged on the outer wall surface near the open end of the
stem 110. The elastic member 130 is prevented from shifting in the
rotating direction by such projections 112.
A fit-in projection 113 for fixing the brush component 200 is also
arranged on the outer wall surface of the stem 110. The inner wall
surface of the tubular portion 201 in the brush component 200 is
formed with an L-shaped groove 203 (see FIG. 4) so as to be fitted
with the fit-in projection 113.
According to such a configuration, the brush component 200 can be
fixed to the stem 110 by axially fitting and then slightly rotating
the tubular portion 201 so that the fit-in projection 113 lies
along the groove 203 of the tubular portion 201.
The holder 120 is a tubular member having an inner diameter larger
than the outer diameter of the stem 110. A plurality of
pass-through holes 121 to which the plurality of lock projections
304a arranged on the motor holder 304 lock, as described above, is
formed near the rear end of the holder 120.
The elastic member 130 includes an interposing portion 132
interposed so as to be sandwiched between the stem 110 and the
holder 120, and a plurality of (three in the present embodiment)
projecting portions 131 arranged so as to project out from a
plurality of pass-through holes 122 formed in the holder 120.
The shape in the direction perpendicular to the axis at the
closely-attached portion of the interposing portion 132 in the
elastic member 130 and the holder 120 is noncircular. In the
present embodiment, a shape cut with a straight line at three
locations is realized with respect to a circle (see FIG. 10). Thus,
the elastic member 130 is prevented from shifting in the rotating
direction with respect to the holder 120.
When the vibration transmitting component 100 configured as above
is attached in the outer case 301, only the plurality of projecting
portions 131 arranged on the elastic member 130 of the vibration
transmitting component 100 contact the inner wall surface of the
outer case 301 by point contact (area contact of very small area).
Therefore, the vibration transmitting component 100 is positioned
only by point contact at a plurality of locations with respect to
the outer case 301. In the present embodiment, three projecting
portions 131 are arranged, as described above, and positioning is
carried out by three point contacts.
<Description on Operation of Electric Toothbrush>
An operation of the electric toothbrush 10 configured as above will
now be described. When the power is turned ON by the switch button
S, the shaft of the motor 305 rotates, and the eccentric shaft
(configured by the shaft main body 306 and the eccentric member
307) fixed to the relevant shaft rotates. The eccentric member 307
is arranged at a position its center of gravity is shifted from the
shaft center.
Therefore, if the eccentric shaft is rotated without the distal end
of the eccentric shaft supported by the bearing 400, the eccentric
member 307 moves so as to turn about the shaft center while
rotating. Thus, if the eccentric shaft is rotated with the
eccentric shaft supported by the bearing 400, an operation is
performed in which the outer wall surface near the distal end of
the eccentric shaft repeatedly hits the inner wall surface of the
bearing 400 for a great number of times in a short period of
time.
According to such an operation, the stem 110 fixed with the bearing
400 can be vibrated through the bearing 400. When the stem 110
vibrates, such vibration can be transmitted to the brush component
200 fixed to the stem 110. Therefore, the brush portion 202
vibrates by the vibration of the brush component 200, and the teeth
can be brushed by placing the brush portion 202 on the teeth.
<Advantages of the Present Embodiment>
Therefore, according to the electric toothbrush 10 of the present
embodiment, the vibration transmitting component 100 is configured
to be positioned with respect to the outer case 301 by point
contacting the inner wall surface of the outer case 301 at the
plurality of locations (three locations in the present
embodiment).
Therefore, the vibration of the vibration transmitting component
100 is suppressed from being transmitted to the outer case 301.
Thus, the outer case 301, which is the portion the user grips with
hand when brushing teeth, is suppressed from vibrating. The user is
then suppressed from feeling unpleasant when brushing teeth.
Since the vibration transmitting component 100 is simply positioned
by point contact at the plurality of locations with respect to the
outer case 301, the movement of the vibration transmitting
component 100 is barely limited by the outer case 301. Thus, the
vibration transmitting component 100 can be freely vibrated without
barely being restricted by the outer case 301. Accordingly, the
loss of vibration energy can be suppressed. Therefore, the
vibration transmitting component 100 as well as the brush component
200 fixed thereto can be greatly vibrated with small power and with
satisfactory efficiency.
Furthermore, in the present embodiment, the vibration transmitting
component 100 is configured by the stem 110 made from a hard
material, the holder 120 made from the same hard material, and the
elastic member 130 made from elastomer, as described above.
The plurality of projecting portions 131 arranged on the elastic
member 130 point contact the inner wall surface of the outer case
301. Therefore, the vibration transmitting component 100
elastically point contacts the inner wall surface of the outer case
301. Thus, the movement of the vibration transmitting component 100
is more reliably prevented from being limited by the outer case
301.
The vibration of the stem 110 is suppressed from being transmitted
to the holder 120 since the interposing portion 132 of the elastic
member 130 is interposed between the stem 110 and the holder 120.
Therefore, the vibration of the stem 110 is transmitted to the
inner case through the holder 120 (more specifically, from the
holder 120 to the inner case main body 303 through the motor holder
304), and such vibration is suppressed from being further
transmitted to the outer case 301.
One reason the vibration of the stem 110 is suppressed from being
transmitted to the holder 120 by interposing the interposing
portion 132 between the stem 110 and the holder 120 is that the
vibration energy is absorbed by the elastic member 130. However,
the present embodiment has features in the configuration in which
the vibration transmitting component 100 can vibrate freely as much
as possible while supporting the vibration transmitting component
100 with the outer case 301 and the inner case.
In other words, a configuration of preventing the vibration from
being transmitted to the outer case 301 by freely vibrating the
vibration transmitting component 100 as much as possible is adopted
instead of preventing the vibration from being transmitted to the
outer case 301 by absorbing the vibration energy. Therefore, the
absorption amount of the vibration energy by the interposing
portion 132 does not need to be large. Therefore, the absorption
amount of the vibration energy by the interposing portion 132 is
set small to an extent that energy loss does not arise as a
problem.
Here, the rotational force may apply to the stem 110 since the
operation of rotating the brush component 200 is involved when
attaching the brush component 200 to the stem 110 (also when
detaching), as described above.
However, in the present embodiment, the vibration transmitting
component 100 can be more reliably fixed to the inner case since
the holder 120 fixed to the inner case is made from a hard
material. Therefore, the holder 120 of the vibration transmitting
component 100 is suppressed from being detached from the inner case
even if the rotational force is applied to the stem 110. More
specifically, the lock projection 304a arranged on the motor holder
304 is suppressed from being detached from the pass-through hole
121 formed in the holder 120.
Moreover, the original function of the vibration transmitting
component of transmitting the vibration generated with the rotation
of the eccentric shaft to the brush portion 202 is sufficiently
exhibited since the stem 110 arranged with the eccentric shaft
bearing 400 is made from a hard material.
In the present embodiment, the elastic member 130 is a molded
article having elastomer as a raw material. In other words, the
vibration transmitting component 100 is obtained by integrally
molding the elastic member 130 by insert molding with the stem 110
and the holder 120 as insert parts.
Therefore, the vibration transmitting component 100 can be handled
as one component, and superior handleability and superior assembly
workability when assembling the electric toothbrush 10 are
obtained. Furthermore, superior sealing property between the stem
110 and the elastic member 130 and between the elastic member 130
and the holder 120 is obtained, and the seal member does not need
to be separately attached or the members do not need to be adhered
by adhesive.
In the present embodiment, the elastic member 130 is prevented from
shifting in the rotating direction with respect to the stem 110 by
arranging the plurality of projections 112 on the outer wall
surface near the open end of the stem 110, as described above. The
elastic member 130 is also prevented from shifting in the rotating
direction with respect to the holder 120 by forming the shape in
the direction perpendicular to the axis at the closely-attached
portion of the holder 120 and the interposing portion 132 in the
elastic member 130 to noncircular.
Therefore, in the present embodiment, a rotation-preventing
structure is arranged between the stem 110 and the elastic member
130, and between the elastic member 130 and the holder 120.
With the use of such a rotation-preventing structure, the
rotational force is sometimes applied to the stem 110 when
attaching or detaching the brush component 200 to and from the stem
110, as described above, but each member is prevented from shifting
in the rotating direction even in such a case. Therefore, the
sealability between the members is suppressed from being
impaired.
(Second Embodiment)
FIG. 11 shows a second embodiment of the present invention. A case
of configuring the holder with a hard material to more reliably fix
the holder and the inner case has been described in the first
embodiment.
However, the fixing force of the holder with respect to the inner
case does not need to be set as high in some cases such as when
configured so that the rotational force does not apply to the
stem.
In the present embodiment, an example when configuring the portion
of the holder also with elastomer is shown. The configurations and
effects other than the vibration transmitting component are the
same as the first embodiment, and thus the description thereof will
be omitted.
FIG. 11 is a cross-sectional view of a vibration transmitting
component according to the second embodiment of the present
invention. The cross-section in FIG. 11 shows the cross-section of
the same position as FIG. 8 shown in the first embodiment.
A vibration transmitting component 100a according to the present
embodiment is configured by the stem 110 made from a hard material
(e.g., resin material), and a holder 140 having elastomer as a raw
material. In the vibration transmitting component 100a according to
the present embodiment, the holder 140 is a molded article molded
by a die. That is, the vibration transmitting component 100a is
obtained by integrally molding the holder 140 by insert molding
with the stem 110 as the insert part.
The configuration of the stem 110 is the same as the first
embodiment, and thus the description thereof will be omitted. In
the present embodiment, the portion corresponding to the holder 120
in the first embodiment and the portion corresponding to the
elastic member 130 are integrated to configure the holder 140. A
plurality of projecting portions 141 is arranged on the holder 140.
Such projecting portions 141 exhibit the same function as the
projecting portion 131 arranged on the elastic member 130 of the
first embodiment.
A plurality of pass-through holes 142 is formed near the rear end
of the holder 140. The pass-through holes 142 are similar to the
case of the first embodiment in being locked by the lock projection
304a arranged on the motor holder 304.
Therefore, effects similar to the case of the first embodiment are
obtained even when the vibration transmitting component 100a
according to the present embodiment is adopted other than that the
fixing force of the holder with respect to the inner case is
inferior to the first embodiment.
(Third Embodiment)
FIG. 12 shows a third embodiment of the present invention. In the
first and second embodiments, a case of configuring the vibration
transmitting component so as to elastically point contact the inner
wall surface of the outer case and so as to interpose a member
having elastomer as a raw material between the stem and the inner
case has been described.
However, the vibration transmitting component can be vibrated
freely to a certain extent and transmission of vibration to the
outer case can be prevented to a certain extent even if the portion
to point contact is hard as long as the vibration transmitting
component can be contacted by point contact to the inner wall
surface of the outer case. Furthermore, the vibration transmitted
to the inner case does not become a large problem in some
cases.
Therefore, in the present embodiment, an embodiment of a case in
which the vibration transmitting component is configured by a
single member made from a hard material is shown. The
configurations and effects other than the vibration transmitting
component are the same as the first embodiment, and thus the
description thereof will be omitted.
FIG. 12 is a cross-sectional view of a vibration transmitting
component according to the third embodiment of the present
invention. The cross-section in FIG. 12 shows the cross-section of
the same position as FIG. 8 shown in the first embodiment.
A vibration transmitting component 100b according to the present
embodiment is configured by a single member made from a hard
material (e.g., resin material). The vibration transmitting
component 100b is integrally configured by a hard material from the
portion corresponding to the stem 110, the portion corresponding to
the holder 120, and the portion corresponding to the elastic member
130 in the first embodiment.
Therefore, the vibration transmitting component 100b according to
the present embodiment also includes a stem portion 150
corresponding to the stem in each embodiment, similar to each
embodiment above. A fixing portion 151 for fixing the bearing 400
is arranged at the distal end in the interior of the stem portion
150. A plurality of projecting portions 152 and a plurality of
pass-through holes 153 are arranged at the position corresponding
to the holder. The projecting portion 152 exhibits functions
similar to the projecting portion arranged on the elastic member
130 in the first embodiment. The pass-through hole 153 is locked by
the lock projection 304a arranged on the motor holder 304.
Therefore, effects similar to the case of the first embodiment are
basically obtained even when adopting the vibration transmitting
component 100b according to the present embodiment although the
vibration transmission suppressing ability is inferior to the first
embodiment. In the case of the present embodiment, the vibration
transmitting component 100b is configured by a single member, and
thus an advantage in that the configuration is more simplified than
the first embodiment is obtained.
(Fourth Embodiment)
FIG. 13 shows a fourth embodiment of the present invention. In the
present embodiment, an embodiment of using a space region formed at
the distal end of the eccentric shaft as an oil reservoir for
storing lubricant oil serving as a lubricant will be described.
Same reference numerals are denoted for the same configuring
portions in each embodiment described above, and the description
thereof will be appropriately omitted.
FIG. 13 is one part of a schematic cross-sectional view of the
electric toothbrush according to the fourth embodiment of the
present invention. In FIG. 13, the encircled figure is a view
enlarging the vicinity of the bearing.
As described in the first embodiment, the bearing 400 is arranged
near the distal end in the interior of the stem 110 configuring the
vibration transmitting component 100. The distal end of the
eccentric shaft configured by the shaft main body 306 and the
eccentric member 307 (more specifically, distal end of the
eccentric member 307) is supported in a freely rotating manner by
the bearing 400.
A space region 115 is formed on the distal end side than the
eccentric shaft at the distal end portion in the interior of the
stem 110. Forming the space region 115 is the same in each
embodiment described above as apparent from the figures referenced
up to now.
In the present embodiment, a configuration of using the space
region 115 as an oil reservoir for storing the lubricant oil O is
adopted. In other words, the lubricant oil O is interposed as the
lubricant at the slidably moving portion X of the eccentric shaft
and the bearing 400.
However, the lubricant oil O gradually decreases through use over
time. Thus, the quality lowers such as the slidable movement
resistance gradually increases, the operation sound becomes louder,
and the vibration increases. Accordingly, the lubricant oil is
supplied to the slidably moving portion X as necessary by storing
the lubricant oil O in the space region 115, as described
above.
Therefore, the lubricant oil O can be interposed over a long period
of time at the slidably moving portion X. The slidably moving state
of the eccentric shaft and the bearing 400 thus can be stabilized
over a long period of time. Therefore, the vibration state of each
portion can be stabilized over a long period of time. Moreover,
increase in the slidable movement resistance can be suppressed, the
generation of abnormal noise (operation sound) can be suppressed,
and increase in vibration can be suppressed. The current
consumption can also be reduced.
In the present embodiment, the distal end 307a of the eccentric
shaft projects out to the space region 115 side than the bearing
400. Thus, the vicinity of the front end 307a of the eccentric
shaft is in a state of contacting the lubricant oil O. The
lubricant oil O thus can be actively introduced (drawn) into the
slidably moving portion X of the eccentric shaft and the bearing
400. Therefore, the lubricant oil O can be stably supplied to the
slidably moving portion X.
The bearing 400 is arranged as a separate member near the distal
end in the interior of the stem 110 to enhance abrasion resistance.
That is, sufficient abrasion resistance may not be obtained with
the raw material (e.g., POM) suited for the stem 110. Therefore, in
the present embodiment, the bearing 400 using the raw material
excelling in abrasion resistance is arranged. Oleoresin, oil
retaining metal, or the like can be suitably applied for the raw
material of the bearing 400. The concentricity can be easily
enhanced by arranging the bearing 400 as a separate member.
(Fifth Embodiment)
FIGS. 14 to 18 show a fifth embodiment of the present invention. In
the present embodiment, a configuration of further suppressing the
transmission of vibration to the portion the user grips with hand
when brushing teeth will be described. The configuration shown in
the present embodiment is a configuration adopted in each
embodiment above as illustrated in most of the figures referenced
up to now, but will be more specifically described in the present
embodiment. Same reference numerals are denoted for the same
configuring portions as in each embodiment described up to now, and
the description thereof will be appropriately omitted.
FIG. 14 is one part of a schematic cross-sectional view of the
electric toothbrush according to the fifth embodiment of the
present invention. FIG. 15 is a partial perspective view of the
vicinity of the brush component of the electric toothbrush
according to the fifth embodiment of the present invention. FIG. 16
is a partial perspective side view of the vicinity of the brush
component of the electric toothbrush according to the fifth
embodiment of the present invention. FIG. 17 is a partially cut
perspective view of the brush component of the electric toothbrush
according to the fifth embodiment of the present invention. The cut
plane in FIG. 17 corresponds to the cross-section of AA in FIG. 16.
FIG. 18 is a view describing the contacting state of the brush
component and the stem in the electric toothbrush according to the
fifth embodiment of the present invention. The cross-sectional view
of the brush component in FIG. 18 corresponds to the cross-section
of AA in FIG. 16.
As described in the first embodiment, the brush component 200 is
attached to the vibration transmitting component 100 so as to cover
the vibration transmitting component 100. As already described
above, the brush component 200 includes the tubular portion 201 to
be attached to the vibration transmitting component 100 and the
brush portion 202 arranged at the distal end of the tubular portion
201. The brush component 200 is a consumable part, and is
configured to be removable with respect to the vibration
transmitting component 100 so as to be appropriately changed with a
new one.
When the brush component 200 is attached to the vibration
transmitting component 100, the vicinity of the front end F and the
vicinity of the rear end R of the tubular portion 201 contact the
stem 110, and a clearance C is formed between the inner wall
surface of the tubular portion 201 and the outer wall surface of
the stem 110 at the intermediate portion.
At the portion where the tubular portion 201 and the stem 110
contact, such contact is point contact (or line contact) at the
plurality of locations with respect to the peripheral direction. It
is, obviously, physically impossible to contact at a perfect point
or line when referring to "point contact" or "line contact", and
contact is made, in reality, at a surface of a very small area.
Therefore, it is actually referring to contacting at as small as
possible surface.
The contacting state will be more specifically described. FIGS. 17
and 18 show cross-sections of the tubular portion 201 in a region
where the tubular portion 201 and the stem 110 contact at the
vicinity of the front end F of the tubular portion 201.
In the present embodiment, a plane portion 201a is formed at three
locations on the inner wall surface in the vicinity of the front
end F of the tubular portion 201. Thus, the cross-sectional shape
perpendicular to the axis at the inner wall surface of the tubular
portion 201 is designed such that most of the portions are
circular, but one part (three locations) of the circle is linear at
the vicinity of the front end F.
The outer wall surface of the stem 110 is formed with a tapered
surface such that the diameter becomes smaller towards the distal
end, and the cross-sectional shape perpendicular to the axis is
circular at all portions. 110X shown with a dotted line in FIG. 18
is the position of the surface of the outer wall surface of the
stem 110.
According to the above configuration, the stem 110 contacts only
the plane portion 201 a at three locations on the inner wall
surface of the tubular portion 201, as shown in FIG. 18, at the
vicinity of the front end F of the tubular portion 201. Therefore,
at the vicinity of the front end F of the tubular portion 201, the
tubular portion 201 and the stem 110 point contact or line contact
at three locations with respect to the peripheral direction.
At the vicinity of the rear end R of the tubular portion 201, the
tubular portion 201 and the stem 110 are configured to point
contact or line contact only at the portion of the L-shaped groove
203 arranged on the tubular portion 201 and the fit-in projection
113 arranged on the stem 110 described in the first embodiment. The
L-shaped groove 203 and the fit-in projection 113 are respectively
arranged at two locations with respect to the peripheral
direction.
Therefore, at the vicinity of the rear end R of the tubular portion
201, the tubular portion 201 and the stem 110 point contact or line
contact at two locations with respect to the peripheral
direction.
According to the present embodiment, the location the vibration is
directly transmitted from the vibration transmitting component 100
to the brush component 200 may be a limited portion (i.e.,
contacting portion), as described above. Therefore, the efficiency
of the vibration transmission with respect to the brush portion 202
can be enhanced as much as possible, and the transmission of
vibration to the portion the user grips with hand when brushing
teeth can be suppressed.
In particular, in the present embodiment, the tubular portion 201
and the stem 110 contact the vicinity of the eccentric shaft
bearing 400 (vicinity of the front end arranged with the brush
portion 202), which is a factor that generates vibration. Thus, the
vibration can be transmitted extremely efficiently with respect to
the brush portion 202. The transmission of the vibration to the
rear end side then can be suppressed, and the transmission of the
vibration to the portion the user grips with hand when brushing
teeth can be effectively suppressed.
The reason the efficiency of vibration transmission to the brush
portion 202 can be enhanced by contacting the tubular portion 201
and the stem 110 only at two locations of the vicinity of the front
end F and the vicinity of the rear end R, and forming the clearance
C at the intermediate portion so that they do not contact will be
described in further detail below.
Considering only the aspect of vibration transmission, the brush
component 200 is ideally held by the vibration transmitting
component 100 with the tubular portion 201 and the stem 110
contacted only at the vicinity of the eccentric member 307
(vicinity of the front end F) near the brush portion 202. However,
if the contacting portion of the tubular portion 201 and the stem
110 is only at the vicinity of the front end F, the holding force
of holding the brush component 200 is not sufficiently obtained,
and the brush component 200 may detach from the vibration
transmitting component 100 while the user is brushing teeth.
Therefore, the brush component 200 is held with the tubular portion
201 and the stem 110 contacted at two locations of the vicinity of
the front end F and the vicinity of the rear end R, as described
above. The brush component 200 thus does not detach during use, and
the brush component 200 can be stably held by the vibration
transmitting component 100.
If the tubular portion 201 and the stem 110 are contacted in a
large area such as when the clearance C is eliminated, the
vibration on the stem 110 side is transmitted to the entire tubular
portion 201. The efficiency of the vibration transmission to the
vicinity of the brush portion 202 thus lowers. The reason of
contacting at two locations of the vicinity of the front end F and
the vicinity of the rear end R is as described.
In the present embodiment, the shaft main body 306 of the eccentric
shaft is configured by a first shaft member 308 connected to the
eccentric member 307, and a second shaft member 309 connected to
the side opposite to the eccentric member 307 with respect to the
first shaft member 308 and having higher flexibility than the first
shaft member 308.
The second shaft member 309 has a first fit-in portion 309a to be
fitted with a distal end of the first shaft member 308 at one end,
and a second fit-in portion 309b to be fitted with a distal end of
a shaft on the motor side serving as a drive source on the other
end.
A small diameter portion 309c smaller than the outer diameter of
the first shaft member 308 is arranged between the first fit-in
portion 309a and the second fit-in portion 309b. The material used
for the first shaft member 308 may be the same material as for the
eccentric member 307. For instance, the material may be a metal
having high specific gravity such as brass or tungsten.
It may be configured with resin different from the eccentric member
307. For instance, a material that is not as hard as metal of high
specific gravity such as polycarbonate (PC) is suitably used.
Elastomer represented by TPE (thermoplastic elastomer) is suitable
for the material of the second shaft member 309. When configuring
the first shaft member 308 with resin and the second shaft member
307 with elastomer, they can be formed by integral molding while
enhancing the manufacturing efficiency.
Therefore, the vibration can be absorbed by the second shaft member
309 by configuring the motor side of the shaft main body 306
configuring the eccentric shaft by the second shaft member 309 of
high flexibility. Thus, the vibration at the portion of the second
shaft member 309 can be absorbed in the process the vibration
generated at the portion of the eccentric member 307 is transmitted
to the rear end side through the eccentric shaft. Therefore, the
transmission of the vibration to the side of the portion the user
grips with hand when brushing teeth can be suppressed through the
eccentric shaft from the eccentric member 307 side.
The transmission amount (vibration absorption amount) of the
vibration can be adjusted (optimized) by adjusting the axial length
and diameter of the small diameter portion 309c. Other effects such
as below are obtained in addition to the vibration absorption
effect by configuring part of the shaft main body 306 by the second
shaft member 309 of high flexibility.
In other words, when using the electric toothbrush 10 according to
the present embodiment, the user brushes teeth so as to press the
distal end of the brush portion 202 against the teeth. Therefore,
some users are assumed to press the brush portion 202 against the
teeth with a force stronger than necessary. In this case, the
eccentric shaft rotates in a bent state while involving vibration
by eccentricity with a position (around an output shaft of the
motor) distant from the acting point at where the force acts as a
supporting point. Therefore, load is imposed on the bent portion
(portion of the supporting point), and breakage easily occurs by
degradation over time, which becomes the cause of shorter
lifespan.
In the present embodiment, the portion close to the distal end of
the shaft on the motor side of the eccentric shaft is configured by
the second shaft member 309 of high flexibility, so that the
portion of the second shaft member 309 (in particular, small
diameter portion 309c) bends when the eccentric shaft bends. Thus,
even if used in the bent state, degradation is less likely to occur
over time (breakage is less likely to occur). The small diameter
portion 309c is also the portion that can effectively absorb
vibration.
As described above, the configuration in which the tubular portion
201 and the stem 110 are contacted only at the vicinity of the
front end F and the vicinity of the rear end R and the clearance C
is formed in the intermediate portion, and the configuration in
which the shaft main body 306 of the eccentric shaft includes the
first shaft member 308 and the second shaft member 309 having
higher flexibility than the first shaft member 308 are also used in
each embodiment described above.
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